ci/x86: speed up piglit testing

Add python3 packages to speed up piglit run.

 - lxml. An accelerated python xml library using libxml2 (http://lxml.de/)
 - simplejson. A fast C based implementation of the python json library.
   (https://simplejson.readthedocs.org/en/latest/)

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7379>
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 7db3ebc..4b9877c 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -352,7 +352,7 @@
 x86_test-gl:
   extends: .use-x86_test-base
   variables:
-    FDO_DISTRIBUTION_TAG: &x86_test-gl "2020-10-09-spvtools-1"
+    FDO_DISTRIBUTION_TAG: &x86_test-gl "2020-10-30-python3-modules-1"
 
 # Debian 10 based x86 test image for VK
 x86_test-vk:
diff --git a/.gitlab-ci/container/x86_test-gl.sh b/.gitlab-ci/container/x86_test-gl.sh
index b97ea72..c8b87ff 100644
--- a/.gitlab-ci/container/x86_test-gl.sh
+++ b/.gitlab-ci/container/x86_test-gl.sh
@@ -42,6 +42,8 @@
       libclang-cpp10 \
       libxcb-shm0 \
       ocl-icd-libopencl1 \
+      python3-lxml \
+      python3-simplejson \
       $STABLE_EPHEMERAL